Aims: Protein S-glutathionylation, the formation of a mixed disulfide between glutathione and protein thiols, is an oxidative modification that has emerged as a new signaling paradigm, potentially linking oxidative stress to chronic inflammation associated with heart disease, diabetes, cancer, lung disease, and aging. Using a novel, highly sensitive, and selective proteomic approach to identify S-glutathionylated proteins, we tested the hypothesis that monocytes and macrophages sense changes in their microenvironment and respond to metabolic stress by altering their protein thiol S-glutathionylation status.
Results: We identified over 130 S-glutathionylated proteins, which were associated with a variety of cellular functions, including metabolism, transcription and translation, protein folding, free radical scavenging, cell motility, and cell death. Over 90% of S-glutathionylated proteins identified in metabolically stressed THP-1 monocytes were also found in hydrogen peroxide (H2O2)-treated cells, suggesting that H2O2 mediates metabolic stress-induced protein S-glutathionylation in monocytes and macrophages. We validated our findings in mouse peritoneal macrophages isolated from both healthy and dyslipidemic atherosclerotic mice and found that 52% of the S-glutathionylated proteins found in THP-1 monocytes were also identified in vivo. Changes in macrophage protein S-glutathionylation induced by dyslipidemia were sexually dimorphic.
Innovation: We provide a novel mechanistic link between metabolic (and thiol oxidative) stress, macrophage dysfunction, and chronic inflammatory diseases associated with metabolic disorders.
Conclusion: Our data support the concept that changes in the extracellular metabolic microenvironment induce S-glutathionylation of proteins central to macrophage metabolism and a wide array of cellular signaling pathways and functions, which in turn initiate and promote functional and phenotypic changes in macrophages. Antioxid. Redox Signal. 25, 836-851.
Keywords: S-glutathionylation; atherosclerosis; macrophage; proteomics; thiols.